global_settings {
   assumed_gamma 1

   max_trace_level 50
   radiosity {}
}

camera{
  location <5, 9, 11>
  up       <0, 1, 0>
  right    <1, 0, 0>
  look_at  <0, -1, 0>
}

sphere {
  0, 10000

  hollow
  no_shadow

  pigment { rgb 1 }
  finish { diffuse 0 ambient 1 }
}

#local fchecker = function { pigment { checker } }

union{
  cylinder{ <-5,  3, -3>, <5,  3, -3>, 1/8 }
  cylinder{ <-5,   0, -3>, <5,   0, -3>, 1/8 }
  cylinder{ <-5, -3, -3>, <5, -3, -3>, 1/8 }

  cylinder{ <-5,  3, 0>, <5,  3, 0>, 1/8 }
  cylinder{ <-5,   0, 0>, <5,   0, 0>, 1/8 }
  cylinder{ <-5, -3, 0>, <5, -3, 0>, 1/8 }

  cylinder{ <-5,  3, 3>, <5,  3, 3>, 1/8 }
  cylinder{ <-5,   0, 3>, <5,   0, 3>, 1/8 }
  cylinder{ <-5, -3, 3>, <5, -3, 3>, 1/8 }

  cylinder{ < 3, -5, -3>, < 3, 5, -3>, 1/8 }
  cylinder{ <  0, -5, -3>, <  0, 5, -3>, 1/8 }
  cylinder{ <-3, -5, -3>, <-3, 5, -3>, 1/8 }

  cylinder{ < 3, -5, 0>, < 3, 5, 0>, 1/8 }
  cylinder{ <  0, -5, 0>, <  0, 5, 0>, 1/8 }
  cylinder{ <-3, -5, 0>, <-3, 5, 0>, 1/8 }

  cylinder{ < 3, -5, 3>, < 3, 5, 3>, 1/8 }
  cylinder{ <  0, -5, 3>, <  0, 5, 3>, 1/8 }
  cylinder{ <-3, -5, 3>, <-3, 5, 3>, 1/8 }

  cylinder{ <-3,  3, -5>, <-3,  3, 5>, 1/8 }
  cylinder{ <-3,   0, -5>, <-3,   0, 5>, 1/8 }
  cylinder{ <-3, -3, -5>, <-3, -3, 5>, 1/8 }

  cylinder{ <0,  3, -5>, <0,  3, 5>, 1/8 }
  cylinder{ <0,   0, -5>, <0,   0, 5>, 1/8 }
  cylinder{ <0, -3, -5>, <0, -3, 5>, 1/8 }

  cylinder{ <3,  3, -5>, <3,  3, 5>, 1/8 }
  cylinder{ <3,   0, -5>, <3,   0, 5>, 1/8 }
  cylinder{ <3, -3, -5>, <3, -3, 5>, 1/8 }

  quadric{ <1, 0, 1>, 0, 0, -1/4 }

  texture{ function { fchecker(x, y, z).gray }
   texture_map{
    [0 pigment {rgb 0 } finish { reflection {0, 1/2 metallic 1/2} 
ambient 0 diffuse 1 }]
    [1 pigment {rgb 0.8 } finish { reflection {0, 1 metallic 1/2} 
ambient 0 diffuse 1 }]
   }
  }
}

Rendering settings: 1000x1000, no AA.

The rendering freezes for several hours on 27%.

POV-Ray v3.6.1.icl8.win32

William

Post a reply to this message

Yup I get it too:

I tried it different ways using a custom build of 3.6.0 (just a bug fix of
the "Identifier expected. - Incomplete function call or spline call found
instead" bug).  Not knowing what it'd look like and wanting to move things
along quicker I started with max_trace_level 5 and it rendered fine at the
same 1000x1000 no AA.  Then:

max_trace_level 5  & radiosity = renders fine at 1000x1000 no AA
max_trace_level 50 & radiosity = stops at 27% just like you said
(or 28% if 800x800)
max trace_level 5  no radiosity = renders fine at 1000x1000 no AA
max_trace_level 50 no radiosity = renders fine at 1000x1000 no AA

Leaving both max_trace_level at 50 and radiosity on:
500x500 stops at 27%  499^2 and 501^2 both render fine.
600^2 renders fine.  700^2 stops at 12%  699^2 stops at 28%
701^2 stops at 26% 698^2 renders fine.

700^2 renders fine with the camera moved to <5,9,11.1>

Charles

William Peska <wil### [at] yahoocom> wrote:
> global_settings {
>    assumed_gamma 1
>
>    max_trace_level 50
>    radiosity {}
> }
>
> camera{
>   location <5, 9, 11>
>   up       <0, 1, 0>
>   right    <1, 0, 0>
>   look_at  <0, -1, 0>
> }

Post a reply to this message

The bug is in the quartic, it appears
not to work predicably with radiosity
(even if you bound it).

The easy solution is just to replace it
with a long cylinder...

Post a reply to this message

Tim Attwood wrote:
> The bug is in the quartic, it appears
> not to work predicably with radiosity
> (even if you bound it).

The bug remains if the quartic is replaced with isosurface:

  isosurface{
   function { x*x + z*z - 1/4 }
   contained_by { box{ <-1, -5, -1>, <1, 5, 1> } }
   max_gradient 8
  }

> The easy solution is just to replace it
> with a long cylinder... 

This will not fix the bug.
I have a scene with isosurface (which can not be replaced), in which the 
rendering freezes during a radiosity pre-trace pass.

William

Post a reply to this message

The line
#local fchecker = function { pigment { checker } }
probably should have been
#local fchecker = function { pigment { checker 0 1} };
The default colors for a checker pigment are green
and blue. Since you later evaluate the gray values,
which should be nearly equal, I think somewhere
the pov engine gets confused.

After making this change it rendered fine for me
at 1000x1000 no AA and default radiosity (23 sec)

Post a reply to this message

Tim Attwood wrote:
> The line
> #local fchecker = function { pigment { checker } }
> probably should have been
> #local fchecker = function { pigment { checker 0 1} };
> The default colors for a checker pigment are green
> and blue. Since you later evaluate the gray values,
> which should be nearly equal, I think somewhere
> the pov engine gets confused.

With the following definitions of fchecker the problem remains:

#local fchecker = function { 0.11 + 0.48*(sin(pi*x)*sin(pi*y)*sin(pi*z) 
< 0) }

#local fchecker = function { 0.11 + 0.48*(sin(3*x)*sin(3*y)*sin(3*z) < 0) }

William

Post a reply to this message

They worked OK for me with max_trace_level 10
instead of 50. I think when you are dealing with
multiple reflections there is a chance of getting
something like a hall of mirrors effect...
possibly 2^max_trace_level rays per pixel.

Post a reply to this message

Tim Attwood wrote:
> They worked OK for me with max_trace_level 10
> instead of 50. I think when you are dealing with
> multiple reflections there is a chance of getting
> something like a hall of mirrors effect...
> possibly 2^max_trace_level rays per pixel. 

That really explains why if the quadric is replaced with:

cylinder{ <  0, -5, 0>, <  0, 5, 0>, 1/2 }

there is no problem.

Thanks for your deep insights. I think that it is a responsibility of 
the POV-Ray developers to figure out their bugs. I wasted enough time.

William

Post a reply to this message

William Peska <wil### [at] yahoocom> wrote:
> Thanks for your deep insights. I think that it is a responsibility of 
> the POV-Ray developers to figure out their bugs. I wasted enough time.

  Do you really think sarcasm is going to solve things?

  People tried to help you and wrote about their ideas on the subject,
and you thank them with sarcasm. With that kind of attitude you are
only going to get people annoyed.

-- 
                                                          - Warp

Post a reply to this message

Warp wrote:
>   People tried to help you and wrote about their ideas on the subject,
> and you thank them with sarcasm.

1. This is a bug report, not a request for help. I nowhere asked for 
help in the two "[bug]" titled posts. I posted this post here because 
povray.bugreports is moderated (so far my post titled "Very slow 
rendering" from 26.1.2007 does not exist there).

2. There is only one on who I "thanked". So your statement is false.

 > With that kind of attitude you are only going to get people annoyed.

3. Have you considered the possibility that your answer "The source code 
is there. Just implement it yourself." may also annoy?

William

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